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The Personal System/2 or PS/2 was IBM's third generation of personal computers released in 1987. It officially replaced the IBM PC, XT, AT, and PC Convertible in IBM's lineup. The PS/2 line was created by IBM in an attempt to recapture control of the PC market by introducing an advanced yet proprietary architecture. IBM's considerable market presence plus the reliability of the PS/2 ensured that the systems would sell in relatively large numbers, especially to large businesses. However the other major manufacturers balked at IBM's licensing terms to develop and sell compatible hardware, particularly as the demanded royalties were on a per machine basis. Also the evolving Wintel architecture was seeing a period of dramatic reductions in price, and so these developments prevented the PS/2 from returning control of the PC market to IBM. However, many of the PS/2's innovations, such as the 16550 UART (serial port), 1440 KB 3.5-inch floppy disk format, 72-pin SIMMs, the PS/2 keyboard and mouse ports, and the VGA video standard, went on to become standards in the broader PC market. The OS/2 operating system was announced at the same time as the PS/2 line and was intended to be the primary operating system for models with Intel 286 or later processors. However, at the time of the first shipments, only PC DOS was available. OS/2 1.0 (text-mode only) and Microsoft's Windows 2.0 became available several months later. IBM also released AIX PS/2, a UNIX operating system for PS/2 models with Intel 386 or later processors. ==Technology== For years before IBM released the PS/2, rumors spread about IBM's plans for successors to its IBM PC, XT, and AT personal computers. Among the rumors that did not come true: * The company would use proprietary, hard-to-copy versions of the Intel 80286 and 80386 processors. * The company would release a version of its VM mainframe operating system for them. * The company would design the new computers to make third-party communications products more difficult to design. IBM's PS/2 was designed to remain software compatible with their PC/AT/XT line of computers upon which the large PC clone market was built, but the hardware was quite different. PS/2 had two BIOSes; one was named ABIOS (Advanced BIOS) which provided a new protected mode interface and was used by OS/2, and the other was named CBIOS (Compatible BIOS) which was included in order for the PS/2 to be software compatible with the PC/AT/XT. CBIOS was so compatible that it even included Cassette BASIC. While IBM did not publish the BIOS source code, it did promise to publish BIOS entry points. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「IBM Personal System/2」の詳細全文を読む スポンサード リンク
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